Dual boot problem. PLEASE HELP

[Villenya]

Hello, i am trying to get dual boot w/ ubuntu and xp. The problem is that i installed ubuntu before xp. After i install xp, i can't boot from ubuntu any more. It automaticly boots xp. i tried to boot with the ubuntu install disk and tried to reinstall GRUB, but errors were displayed and installation failed. I really need to get back onto ubuntu, what do i DO?

Sry wrong section =P

[aysiu]

Have you taken a look at this thread (http://ubuntuforums.org/showthread.php?t=24113)?

And didn't you already post about this here (http://www.ubuntuforums.org/showthread.php?p=372377#post372377)?